Secondary battery

Abstract

A secondary battery includes a cathode; an anode; and an electrolyte between the cathode and the anode, wherein the electrolyte includes a first electrolyte layer including a first polymer, a first lithium salt, and a first particle inorganic material having an average particle diameter (D50) of less than 500 nm; and a second electrolyte layer including a second polymer, a second lithium salt, and a second particle inorganic material having an average particle diameter (D50) of 500 nm or greater, wherein the first electrolyte layer is disposed in a direction facing the anode.

What is claimed is: 
     
       1. A secondary battery, comprising:
 a cathode; 
 an anode; and 
 an electrolyte between the cathode and the anode, 
 wherein the electrolyte includes:
 a first electrolyte layer including a first polymer, a first lithium salt, and a first particle inorganic material having an average particle diameter (D50) of less than 500 nm; and 
 a second electrolyte layer including a second polymer, a second lithium salt, and a second particle inorganic material having an average particle diameter (D50) of 500 nm or greater, 
 
 wherein the first electrolyte layer is in a direction facing the anode. 
 
     
     
       2. The secondary battery as claimed in  claim 1 , wherein the first particle inorganic material in the first electrolyte layer has an average particle diameter (D50) in a range of about 10 nm to about 300 nm. 
     
     
       3. The secondary battery as claimed in  claim 1 , wherein the second particle inorganic material in the second electrolyte layer has an average particle diameter (D50) in a range of about 500 nm to about 1 μm. 
     
     
       4. The secondary battery as claimed in  claim 1 , wherein a total thickness of the first electrolyte layer and the second electrolyte layer is 20 μm or less. 
     
     
       5. The secondary battery as claimed in  claim 1 , wherein a thickness of the first electrolyte layer is less than a thickness of the second electrolyte layer. 
     
     
       6. The secondary battery as claimed in  claim 1 , wherein a thickness of the first electrolyte layer is in a range of about 1 μm to about 10 μm. 
     
     
       7. The secondary battery as claimed in  claim 1 , wherein the first particle inorganic material and the second particle inorganic material each independently include at least one selected from Al 2 O 3 , SiO 2 , TiO 2 , ZnO, BaTiO 3 , and an inorganic composite that is surface modified with an ion conductive oligomer or an ionic salt on a surface thereof. 
     
     
       8. The secondary battery as claimed in  claim 1 , wherein a total amount of the first particle inorganic material and the second particle inorganic material is in a range of about 1 part to 30 parts by weight based on 100 parts by weight of a total amount of the first polymer and the second polymer. 
     
     
       9. The secondary battery as claimed in  claim 1 , wherein the first polymer and the second polymer each independently include at least one selected from polyalkylene oxide, poly(vinylidene fluoride), poly(hexafluoropropylene), polycarbonate, phosphate ester polymers, polyalkylimine, polyacrylonitrile, poly(meth)acrylic acid ester, phosphonitrile chloride, polyurethane, polyamide, polyester, polysiloxane, and a derivative thereof. 
     
     
       10. The secondary battery as claimed in  claim 1 , wherein a weight average molecular weight of the first polymer and the weight average molecular weight of the second polymer are independently in a range of about 100,000 g/mol to about 300,000 g/mol. 
     
     
       11. The secondary battery as claimed in  claim 1 , wherein the first lithium salt and the second lithium salt each independently include at least one selected from LiSCN, LiN(CN) 2 , LiClO 4 , LiBF 4 , LiAsF 6 , LiPF 6 , LiCF 3 SO 3 , Li(CF 3 SO 2 ) 2 N, Li(CF 3 SO 2 ) 3 C, LiN(SO 2 F) 2 , LiN(SO 2 CF 3 ) 2 , LiN(SO 2 CF 2 CF 3 ) 2 , LiSbF 6 , LiPF 3 (CF 2 CF 3 ) 3 , LiPF 3 (CF 3 ) 3 , and LiB(C 2 O 4 ) 2 . 
     
     
       12. The secondary battery as claimed in  claim 1 , wherein a total amount of the first lithium salt and the second lithium salt is in a range of about 50 parts to about 100 parts by weight based on 100 parts by weight of a total amount of the first polymer and the second polymer. 
     
     
       13. The secondary battery as claimed in  claim 1 , wherein the electrolyte includes a solid electrolyte. 
     
     
       14. The secondary battery as claimed in  claim 1 , wherein the electrolyte is in a form of a film or sheet. 
     
     
       15. The secondary battery as claimed in  claim 1 , wherein the anode is a lithium metal or a lithium-containing alloy. 
     
     
       16. The secondary battery as claimed in  claim 1 , wherein the cathode includes at least one cathode active material selected from lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, and lithium manganese oxide. 
     
     
       17. The secondary battery as claimed in  claim 1 , wherein the electrolyte further includes a separator.